Lotus leaves repel water and always stay clean.
Why it is true
The surface of lotus leaves has a microscopic structure that makes water form droplets and slide off, taking dirt with it. This phenomenon, known as the lotus effect, has inspired self-cleaning paints and coatings.
Source: Nature
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.